Project Summary DNA replication is a fundamental process that includes the accurate duplication of the genome as well as the re-establishment of chromatin modifications and epigenetic information. DNA damage interferes with replication fidelity, leading to an accumulation of mutations and chromosomal translocations, which cause genome instability. The DNA damage response (DDR) functions to resolve replication problems by recruiting repair proteins, activating checkpoints and promoting apoptosis. Cancers are characterized by genome instability and have a greater need for functional DDR pathways. This provides opportunities for therapeutic intervention, and in recent years, inhibitors have been developed targeting components of the DDR. The overall goal of this proposal is to elucidate the mechanisms of genome maintenance that operate during DNA replication. To address this broad goal, I propose three aims ? 1) To determine the mechanisms by which the single strand DNA binding protein, RPA, regulates the DDR protein, SMARCAL1 2) Discovery and functional characterization of a novel alternative single strand DNA binding protein and 3) Mechanistic understanding of how DNA repair proteins work in the context of chromatin structure. While aims 1 and 2 will be completed by the end of my pre-doctoral studies, aim 3 represents the research direction I will adopt in my post-doctoral work. To accomplish these aims, I will utilize new methods such as single molecule, genome wide and proteomic approaches, as well as biochemical, molecular and genetic techniques. Completion of the proposed aims will yield significant insights into novel genome maintenance pathways and will further our understanding of the mechanisms underlying cancer biogenesis.